Chapter 7

This set of flashcards covers key concepts regarding cellular respiration, including processes, definitions, and the role of various molecules in energy transfer.

What is the importance of electrons in energy transfer in living systems?

Electrons play a key role in transferring energy during cellular processes, particularly in oxidation-reduction (redox) reactions.

How is ATP used by cells as a source of energy?

ATP serves as the energy currency of the cell, enabling biochemical reactions by releasing energy when converted to ADP.

Define 'oxidation'.

Oxidation is the chemical process that occurs when electrons are lost from a molecule.

Define 'reduction'.

Reduction is the chemical process that occurs when electrons are gained by a molecule.

What is cellular respiration?

Cellular respiration is the set of metabolic reactions that convert biochemical energy from nutrients into ATP and release waste products.

What are the main inputs and outputs of glycolysis?

Inputs: 1 glucose, 2 NAD+, 2 ATP; Outputs: 2 pyruvate, 2 NADH, and 2 ATP (net).

Where does glycolysis occur?

Glycolysis occurs in the cytoplasm of the cell.

What are the two main phases of glycolysis?

The energy investment phase and the energy payoff phase.

How is ATP generated during oxidative phosphorylation?

ATP is generated through oxidative phosphorylation by the electron transport chain and chemiosmosis, utilizing energy from a proton gradient.

What role do coenzymes play in cellular respiration?

Coenzymes act as electron carriers that shuttle electrons during biochemical reactions.

Describe the flow of metabolites and electrons during the citric acid cycle.

Location:

• Mitochondrial matrix

Inputs:

• Acetyl CoA

• NAD⁺

• FAD

Outputs:

• CO₂

• NADH

• FADH₂

• ATP

What is the main function of the electron transport chain?

The electron transport chain couples the energy from electron transfer to pump protons, creating a proton gradient that drives ATP synthesis.

What happens during fermentation?

Fermentation is an anaerobic process that allows cells to produce ATP without oxygen by converting pyruvate into lactic acid or ethanol.

In what situations is lactic acid fermentation used?

Lactic acid fermentation occurs in muscle cells under low oxygen conditions and certain bacteria.

What is the difference between aerobic and anaerobic respiration?

Aerobic respiration requires oxygen and yields more ATP, while anaerobic respiration occurs without oxygen and produces less ATP.

What factors regulate cellular respiration?

Cellular respiration is regulated by allosteric enzymes, feedback inhibition, and the availability of substrates.

How is pyruvate prepared for entry into the citric acid cycle?

Pyruvate is converted into acetyl CoA before entering the citric acid cycle.

Describe the flow of metabolites and electrons during oxidative phosphorylation

Location:

• Inner mitochondrial membrane

Process:

1. NADH & FADH₂ donate electrons

2. Electrons move through ETC

3. Protons (H⁺) pumped → gradient

4. ATP synthase makes ATP

Explain why oxygen is a beneficial electron acceptor.

Oxygen is the final electron acceptor.

Explanation:

• Electrons must go somewhere

• Oxygen accepts them → forms water

Compare ATP synthesis via substrate-level phosphorylation and oxidative phosphorylation

Substrate-level phosphorylation

• Direct transfer of phosphate

• Happens in:

  • Glycolysis

  • Krebs cycle

• Produces little ATP

Oxidative phosphorylation

• Uses ETC + proton gradient

• Produces MOST ATP (~90%)

What are the 2 major types of fermentation.

Lactic acid fermentation and alcohol fermentation